Headache is so common that it is often not regarded as a serious health issue. However, more than 45 million Americans suffer from headaches sever enough to seek medical help.
A study published in the April 1999 issue of the Archives of Internal Medicine revealed that one single headache type, namely migraine, costs American employers $13 billion per year due to missed work and reduced productivity. In addition, according to the National Headache Foundation (NHF), approximately 157 million workdays are lost annually due to the pain and the associated symptoms of migraine. On top of the above mentioned economic impact, there are intangible costs, such the poor quality of life of these headache sufferers due to the time missed from their daily activities.
The International Headache Society (IHS) classifies headache disorders into two main categories: primary and secondary. The main difference between these two categories is that the secondary type headaches are attributed to a particular cause. The twelve headache types within both categories are listed below in Table 1 and a more in detailed comparison of the first three primary headaches can be found in Table 2.
TABLE 1International classification of headache disordersPrimary Headaches1.Migraine2.Tension-type headache (TTH)3.Cluster headache4.Other primary headachesSecondary Headaches5.Headache attributed to head and/or neck trauma6.Headache attributed to cranial or cervical vascular disorder7.Headache attributed to non-vascular intracranial disorder8.Headache attributed to a substance or its withdrawal9.Headache attributed to infection10.Headache attributed to disorder of homeostasis11.Headache or facial pain attributed to disorder of cranium,neck, eyes, ears, nose, sinuses, teeth, mouth or otherfacial or cranial structures12.Headache attributed to psychiatric disorder
TABLE 2Characteristics of Primary Headache DisordersTension-TypeMigraineHeadache (TTH)Cluster HeadacheLocationUnilateralBilateralStrictly unilateralIntensityModerate/severeMild/moderateSevereDuration4 to 72 hoursEpisodic: 3015 to 90 minmin to 7 daysSufferers29.5 million78% of adultOne millionin the U.S.population
Although the overall mechanisms and specific pathways responsible for primary and secondary headaches are still being elucidated, it is well known that many patients that experience these types of headaches often feel pain in both the front and the back of the head. While the front of the head is innervated, among others, by the ophthalmic branch of the trigeminal nerve, the back of the head is mainly innervated by spinal branches arising from C1 through C4, which are the first four cervical spinal nerves and which, among others, form the occipital and suboccipital nerves. However, recent studies suggest that there is a functional connection between the branches of the nervous system that innervate the front and the back of the head.
The most commonly used treatment to mitigate headache pain is to date the pharmacological approach, which, depending on the particular drug, according to the American Council for Headache Education and to the National Guideline Clearinghouse (NGC) has various potential side effects. Some of these side effects include: fatigue, depression, nausea, insomnia, weight gain, constipation, dizziness, low blood pressure, gastrointestinal irritation, impaired platelet function, renal complications, analgesic rebound headache, and hepatic complications.
Studies exploring alternative treatments for headaches have shown that electrically stimulating spinal nerve branches arising from between C1 through C4 provide an effective technique to mitigate several types of headaches. Electrostimulation of other sites in the head has also been successfully used to treat headaches. A study by Solomon et al. used high frequency (12 kHz to 20 kHz) electrostimulation in which one electrode was placed over the area of maximum pain and a second electrode on the opposite side of the head. In the same study, in cases where the pain was generalized, one electrode was placed in the occiput (back of the head) and another on the right hand. Solomon found that fifty-five percent (55%) of patients perceived an improvement a few minutes after the onset of the electrostimulation.
In another study by Ahmed et al., percutaneous electrical nerve stimulation (PENS) was used to treat tension-type headache (TTH), migraine and posttraumatic headache (PTH); this study revealed that, regardless of the type of headache, pain was significantly mitigated; 58%, 58% and 52% in TTH, migraine, and PSH respectively. On top of the pain reduction, a reduction in the frequency of headaches was also observed.
As mentioned above, electrostimulation of the spinal branches arising from C1 through C4 in the occipital and suboccipital region has proven to be effective in mitigating pain and reducing the frequency of occurrence of several types of headaches. However, the approach taken involves the chronic implantation of electrodes into the aforementioned anatomical region along with the implantation of a stimulating unit (sometimes referred to as an implantable pulse generator (IPG)), in a second location or in the same region (see U.S. Pat. No. 6,735,475, which is incorporated herein by reference) to produce the stimulating signal. Several scientific publications assess the effectiveness of this approach (e.g., Manjit et al., 2004; Popeney and Alo, 2003; Schwedt, et al., 2007a; Schwedt, et al., 2007b; Rodrigo-Royo et al., 2005).
U.S. Pat. No. 4,856,526 and U.S. Pat. No. 4,627,438 to Liss et al., which are incorporated herein by reference, describe the approach by Solomon, which includes electrodes fixed to the head, with the inconvenience that cables running from the electrodes to the stimulation unit (pulse generator) are needed. In addition, fixing the electrodes, which are disposable, in place requires the use of non-permanent biocompatible conductive glue.
In the PENS approach, needles have to protrude and penetrate the skin in specific locations and at specific depths, which renders a self treating paradigm nearly impossible. In addition, the PENS approach requires a skilled and well trained person to position the needles. On top of that, cables need to be used to connect the needles to the stimulator unit and the needles are disposable (typically not reusable, or they must be sterilized between uses, adding expense to the use of the PENS approach).
As stated above, although chronic implantation of a stimulator unit and electrodes to treat headaches mitigates pain and disability in most patients, it has the caveat that the patient must undergo a surgical procedure and be left with at least one foreign body chronically implanted. This approach might be acceptable for and by a subpopulation of patients with severe and quasi permanent debilitating headaches; however, the majority of those suffering from debilitating headaches suffer them on average once a month.
Other non-specific approaches such as the one suggested in U.S. Patent Application Publication Number U.S. 2006/0173510 (which is incorporated herein by reference), also has the inconvenience that electrodes have to be fixed and cables have to be used to connect the electrodes to the stimulating unit.
U.S. Pat. No. 5,078,928 (hereinafter, “Balster et al.”), titled “COATING PROCESS FOR MANUFACTURING ENLARGED SMOOTH TEETH ENDS ON COMB”, issued Jan. 7, 1992, describes a process that could be used to manufacture smooth, comb-like electrodes, and is incorporated herein by reference. Balster et al. describe a process for permanently attaching smooth-finished globules of coating material to the ends of the teeth of molded plastic combs, picks, lifts and the like, including roughening or oxidizing the teeth ends to remove the gloss finish and form a more adherent surface; dipping the roughened teeth ends into a bath of liquid coating material to attach a globule of coating material to each tooth end and cover the sharp mold-parting line located thereat; and drying the globules attached to the teeth ends.
Clearly, the majority of the patient population suffering from headaches would benefit from, and what is needed are a self-contained (i.e., one piece with no interconnecting cables and/or wires) portable device and a side-effect-free (e.g., non-pharmaceutical) yet effective non-invasive treatment method that could be self administered via the self-contained portable device that can be used in both preventative and abortive ways. This invention discloses such a device and method.